An unusual pseudosarcomatous lesion of the oral mucosa is described in a 43-year-old woman. It presented as an aggressive ulcerative mass in the mandibular retromolar gingiva of one month's duration. The lesion was composed of florid myofibroblastic and fibrohistiocytic proliferations with infiltrative margins in an inflammatory background and was considered to be an inflammatory pseudotumor. Although the tumor appeared to have been incompletely excised, the patient remains free of disease at 1 year follow-up.